Tightening device for bottom belts of drawing mechanisms for spinning machines

ABSTRACT

A TIGHTENING DEVICE FOR EACH BOTTOM BELT OF A DRAWING MECHANISM FOR A SPINNING MACHINE WHICH IS LOCATED WITHIN THE LOOP OF THE BELT CONNECTING THE BOTTOM-BELT ROLLER WITH THE GUIDE RAIL AND COMPRISES A TIGHTENING BAR WHICH IS PIVOTABLY MOUNTED ON THE GUIDE RAIL AND PRESSES UNDER THE ACTION OF AT LEAST ONE SPRING AGAINST THE INNER SIDE OF THE BELT.

Feb. 16, 1971 F. sTAHLEcKER ETAL 3,562,868

TIGHTENING DEVICE FOR BOTTOM BELTS OF DRAWING MFCHANISMS FOR SPINNING MACHINES Filed June 26, 1968 ig-a M K 1. I

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United States Patent Oflice 3,562,868 Patented Feb. 16, 1971 Int. Cl. Dtilh 5/86 US. Cl. 19-250 17 Claims ABSTRACT OF THE DISCLOSURE A tightening device for each bottom belt of a drawing mechanism for a spinning machine which is located within the loop of the belt connecting the bottom-belt roller with the guide rail and comprises a tightening bar which is pivotably mounted on the guide rail and presses under the action of at least one spring against the inner side of the belt.

The present invention relates to a tightening device for the bottom belts of drawing mechanisms for spinning machines which is mounted on the guide rail for the bottom belt and the tightening elements of which are dispolsled within the loop of the belt adjacent to the bottom r0 er.

There are drawing mechanisms known in which the tightening devices for the bottom belts are not mounted on a separate supporting bar underneath the drawing mechanism but on the .guide rail for the bottom belts. The individual bottom belts are guided by and run over a stationary guide rail or bridge on which tightening elements are mounted which are pivotable relative to the bottom belts about an axis which is in a fixed position relative to the guide rail. The guide rail has a web with reinforcements thereon on which the individual tightening elements are pivotably mounted. This construction has the disadvantage that it requires the guide rail for the belts to be of a particular, substantially T-shaped cross section. It is therefore not possible to employ a guide rail of the conventional angular shape which may be mounted without difiiculty on the supporting posts and which usually guides the bottom belt also to a certain extent in the downward direction. However, the apertures or recesses which are provided in the guide rail for maintaining the tightening elements in a fixed position reduce the solidity of the guide rail. It is a further disadvantage of these known devices that the tightening element which consists of plastic can only be removed with difficulty from the reinforcement of the guide-rail web, since the bearing bore of the latter is open toward the outside at approximately one-fourth of a circle and its arms can therefore be only very slightly resilient so that special means are required for inserting and removing the tightening element or that it may be necessary for this purpose to remove the guide rail.

It is an object of the present invention to provide a tightening device for the lower belt of a drawing mechanism for a spinning machine which eliminates the abovementioned disadvantages of the known tightening devices and may be easily installed and removed. According to the invention, this may be attained by mounting the tightening element which comprises a tightening bar and a pair of lateral supporting arms on a supporting element which is mounted on the guide rail, and by designing this tightening element so as to permit it to be easily installed in or removed from the supporting element by elastically deforming at least one of its two lateral arms.

Due to the short length of the bottom belts and the short distance between the guide rail and the bottom roller of the drawing mechanism according to the invention, there is no danger that the bottom belts might be drawn from above into the gap between the bottom-belt roller and the flat upper surface of the guide rail when for some reason the tightening device fails to be sufiiciently effective, for example, when the movement of the upper belt is blocked. The damages to the bottom belt and the tensioning device which easily occur in the known drawing mechanisms will therefore no longer occur. If it becomes necessary that the tightening element has to be exchanged, this may be done very easily without requiring the guide rail to be removed. In one advantageous embodiment the invention provides that the tightening bar has a pair of arms so as to form a U-shaped tightening yoke and that at least one of these arms is resilient in the longitudi nal direction of the tightening bar. Such a tightening yoke may be easily inserted into and removed from its supporting element without any tools, simply by manually pressing the yoke arms toward each other or by pulling them away from each other. It is then advisable to provide the supporting element with a pair of projections or lugs which serve as pivots for the arms of the tightening yoke which are preferably located on the outer sides of these lugs. Such supporting elements and tightening yokes of plastic or sheet metal may be made so as to take up very little space and to be very smooth so as to pick up very little fly. It is further advisable to make the arms of the tightening yoke of a concave shape in their longitudinal direction so that the different points of the arms facing the bottom-belt roller will be spaced substantially equally and at a short distance from this roller. Due to this construction, the tightening yoke also has a. great solidity and the curved arms also have the advantages of covering up the largest part of the free space at the inner side of the belt. It is further advisable to provide the ends of the arms carrying the tightening bar with lateral guide projections for preventing the bottom belt from sliding off laterally. Since in accordance with the invention the tightening bar is located at a very short distance from the bottom-belt roller, these guide projections will also be very close to this roller and thus also guide the belt very accurately on the roller.

In the tightening device according to the invention it may be advisable to secure the supporting element of the guide rail permanently to the latter, for example, by spot-welding, soldering, riveting, gluing or the like. This may be of advantage especially in a spinning mill in which many spinning machines of the same kind and with equal drawing mechanisms are to be mounted at the same distances from each other. In other cases, for example, when different machines or draw-in mechanisms might be desired, it is of advantage to secure the supporting element of the tightening device resiliently to the guide rail. A very advantageous manner of securing the supporting element consists, for example, of designing this element so as to embrace the web of the guide rail resiliently and to be provided with a projection which engages into a recess in this web. If this construction is employed, not only the tightening elements which are provided, for example, in the form of tightening yokes may be easily installed and removed, but also the supporting elements may be removed from the guide rail.

For tightening the bottom belt, the tightening bar of the device according to the invention is preferably acted upon by springs. According to another feature of the invention, this may be accomplished in a very simple and reliable manner by means of a leaf spring, one end of which is connected to the tightening bar, while its other end presses against the supporting element. The first end of the leaf spring may be made relatively Wide and thin and be very firmly secured to the tightening bar, for example, by being embedded therein when the tightening bar is being die-cast of plastic. The tightening spring may, however, also be provided in the form of a coil spring which acts upon an extension of the tightening element above its pivot axis and is at least partly enclosed by this extension so that the coil spring, which is normally more liable to pick up fly than a leaf spring, will be well protected from fly or other foreign matter by being inserted into a special recess or bore in the tightening element.

A very advantageous combination of the supporting element and the tightening element thereon will be attained if the supporting element consists of sheet steel and the tightening element which is integral with the tightening bar consists of plastic.

According to a further feature of the invention, it may be advisable to provide the tightening bar which consists of plastic with a reinforcing rail. By such a construction it is possible to attain very suitable frictional relations between the tightening bar and the bottom belt and, in addiion, the tightening bar will be reinforced and be more resistant to wear.

The features and advantages of the present invention will become further apparent from the following detailed description thereof which is to be read with reference to accompanying drawings, in which FIG. 1 shows a cross section which is taken along the line II of FIG. 2 of the belt rollers and delivery rollers of a two-belt drawing mechanism which is provided with a tightening device for the bottom belt which consists of a tightening yoke, a supporting element which is secured to the guide rail, and a tightening spring in the form of a leaf spring;

FIG. 2 shows a top view of the tightening device according to FIG. 1, but without the top rollers;

FIG. 3 shows, partly in cross section, a view of the tightening device, as seen in the direction of the arrows IIIHI in FIG. 1;

FIG. 4 shows, partly in section, a view of a tightening device similar to that as shown in FIG. 3, but with a different kind of tightening spring, namely, in the form of a double coil spring, the outer ends of which form supporting arms;

FIG. 5 shows a cross section of a tightening device similar to that as shown in FIG. 1, but provided with a supporting element which is resiliently clamped together with the guide rail;

FIG. 6 shows a cross section along line VI-VI of FIG. 7 of a tightening device similar to that as shown in FIG. 5, but provided with a coil spring which is mounted within a recess in the tightening yoke above the pivot axis of the latter, and with a tightening bar which is provided with a reinforcing pin;

FIG. 7 shows a section which is taken along the line VIIVII of FIG. 6;

FIG. 8 shows a section of the tightening device taken along line VIII-VIII of FIG. 6.

As illustrated in FIGS. 1 and 2, the drawing mechanism according to the invention comprises a guide rail 3 which is mounted in two adjacent supporting posts, not shown, and extends, for example, over six spinning units and is located between the bottom delivery roller 1 andthe bottom-belt roller 2. Guide rail 3 is provided for each spinning unit with a tightening device for a short bottom belt 4. This tightening device consists of a supporting bracket 5, a tightening yoke 6, and tightening spring 7. The supporting bracket 5 which is made of a steel plate is secured to guide rail 3 by spot-welding, as indicated by the welding points 3a on the central web of supporting bracket 5. The tightening yoke 6 is made of plastic and consists of the tightening bar 611 and its two lateral arms 6b which have a concave curvature so that their parts between their pivot axis and the tightening bar 6a will be spaced at a very small distance from the bottom roller 2. For pivotally mounting the yoke 6, its arms 6b are provided with pivot studs 60 which engage from the outside into the bore 5b in the side arms 5a of bracket 5. On its lower outer sides, yoke 6 has a pair of guide projections 6d which prevent the belt 4 from sliding laterally off the yoke. These projections 6d have only such a size that the belt 4 may still be easily slipped over the tightening yoke 6 when the latter is pressed against the bottom roller 2. One end of the tightening spring 7 which consists of a leaf spring is secured to the bar 6a by being molded into the same when the tightening yoke 6 is being die-cast. The free end of spring 7 presses upon the central web of bracket 5 and the back pressure of the other end of the spring then presses the tightening bar 6:: from the inside against the belt 4. For indicating this spring action more clearly, spring 7 is also shown in FIG. 1 in dot-and-dash lines in its released position 7a. Above their pivot studs 6c, the arms 6b of yoke 6 are provided with extensionse 6e which prevent the yoke from turning in the counterclockwise direction beyond the limit determined by the tightening spring by abutting against the guide rail 3. Instead of abutting against the guide rail 3, the arms 6b of yoke 6 may also abut against the central web of bracket 5 if this web is extended on both sides beyond its projections 5a. These tightening devices may be assembled and installed in different manners depending upon whether the entire machine is being newly installed or whether individual units are to be installed or individual belts or tightening elements are to be exchanged. This may be done, for example, in the following manner: The guide rail 3 to which the brackets 5 are welded at intervals in accordance with the spaces between the spindles is kept ready for being used. The required number of bottom belts 4, for example, six belts, are applied on the bottom-belt roller 2 of the machine and are pushed together as to take up approximately one half of the length of the roller between two adjacent supporting posts. For easy replacement it may also be advisable to apply one or two additional belts on the roller 2. Guide rail 3 is inserted into the belts from the side of roller 2 which is not covered by belts and it is then inserted into and secured to its guides on the supporting posts. The belts are then shifted to the smooth neck portion of the roller 2 adjacent to their spinning positions. Thereupon, the tightening yokes 6 are manually inserted from below into the supporting brackets 5. For this purpose, at first one pivot stud 6c is inserted into the corresponding bore 5b in bracket 5 and thereafter the arm carrying the other pivot stud is elastically bent slightly outwardly and its pivot stud is then snapped into the other bore 5b in bracket 5. The belts are slipped over the tightening yokes 6 and their guide projections 6d to their operative positions and for this purpose the yokes 6 are pressed temporarily against the bottom-belt roller 2. When an entire machine is being newly intsalled, it may be advisable to deviate from the above method by first distributing the endless belts in a suitable manner on the lower roller 2 before the same is installed. Thereafter the guide rails are inserted into the belts and then the belts are distributed on the neck portions of roller 2 adjacent to their spinning positions. The yokes 6 are then hooked into the brackets 5 and the belts 4 are slipped laterally over them. Thereafter the bottom roller with the tightening devices together with the guide rail suspended in its belts is inserted into the supporting posts. The guide rail is then slightly tightened and likewise inserted into and secured to its guides in the supporting posts.

When a new belt which is still open is applied next to the spinning position to the bottom roller after the latter is installed and the ends of the belt are then welded together by means of a special tool, it may be easily slipped over its tightening yoke 6. The tightening yoke may be easily removed at the spinning position since, after removing the belt or shifting it laterally, it is for this purpose only necessary to press with a finger against one arm 6b in the outward direction. The tightening devices according to the invention may therefore be easily installed or removed even though the belts 4 are very short as compared with the width of the drawing mechanisms and even though the tigthtening bars 6a are located very closely adjacent to the bottom roller 2.

FIG. 4 illustrates a modification of the invention, in which the tightening yoke 46 is snapped from the inside into the slide arms 45a of the supporting bracket 45. The tightening spring 47 consists of a double coil spring which is mounted on the projections 46d of the arms 46b of the tightening yoke 46. The two outer ends of spring 47 form straight spring arms 47a the ends of which are bent over and engage into recesses 460 in the arms 46b of the tightening yoke. By means of its central connecting bow 47b, spring 47 is supported on the central web of bracket 45. The characteristic of the spring 47 which is removable from the tightening yoke may be very soft. It is, however, slightly more difficult to produce this spring 47 than the leaf spirng 7 according to FIG. 3.

According to the further modification of the invention as illustrated in FIG. 5, the supporting bracket 55 has a resilient central part of a substantially V-shaped cross section, the arm 55b of which has a pair of lateral guide projections 55a on which the tightening yoke 56 is pivotably mounted. This arm 55b is bent slightly inwardly at its upper end thereby forming a projection which engages into a continuous recess 53a in guide rail 53. The left arm 55c engages under tension upon the slightly recessed surface 53b of the guide rail. This supporting bracket 55 may have a very strong spring action and therefore, when it is fully inserted from below into the guide rail it will be firmly locked to the guide rail by embracing a part thereof. After being installed it is then, however, still possible to shift the supporting bracket laterally by means of a special tool and after the guide rail has been removed, it is also easily possible to remove the supporting bracket entirely from the guide rail by pushing the projection of its right arm 55b by means of a special tool out of the recess 53a.

According to the further embodiment of the invention as illustrated in FIGS. 6 and 7, the tightening yoke 66 which consists of plastic has two lateral arms 66b which may be snapped resiliently from the inner side into the supporting bracket 65. The bottom belt 64 is tightened by a pin 66 which is partly embedded in the tightening bar 66a of yoke 66 which has a slightly larger than semicircular cross section and the slightly resilient arms 66e of which securely grip the pin 66f. The end surfaces of pin 66f abut against the lateral projections 66d of the tightening yoke. In order to facilitate a removal of pin 66 when necessary, its bed 66c is provided with recesses 66g, as illustrated in FIG. 8, into which a pointed tool may be inserted to engage behind the pin 66 to push the same outwardly. The supporting bracket 65 is secured to the guide rail 63 by means of a pair of screws 63a. The tightening spring 67 in the form of a coil spring is mounted in a recess 6611 in an extension 66i of the yoke 66 and presses above the pivot axis of the latter upon the central web of bracket 65. This coil spring 67 as well as the pin 66] may be easily exchanged for others when their renewal becomes necessary.

Although our invention has been illustrated and described with reference to the preferred embodiments thereof, we wish to have it understood that it is in no way limited to the details of such embodiments but is capable of numerous modifications within the scope of the appended claims.

Having thus fully disclosed our invention, what we claim is:

1. A tightening device for the bottom belt of a drawing mechanism for a spinning machine having a bottom roller and a guide rail closely adjacent to said roller so that said belt runs over said roller and said guide rail and forms a loop underneath said roller and guide rail, said tightening device comprising tightening means for tighten ing the belt disposed within said loop at the inner side of said belt and including a tightening bar adapted to engage upon said belt and having a pair of lateral arms, a supporting member mounted on said guide rail, and means for pivotably mounting said arms on said supporting member, at least one of said arms being adapted to be elas tically deformed for easily mounting said tightening means on said supporting member and for easily removing it therefrom.

2. A tightening device as defined in claim 1, wherein said tightening bar together with its two lateral arms forms a yoke-shaped element, at least one of said arms being resilient in a direction substantially parallel to the longitudinal direction of said tightening bar.

3. A tightening device as defined in claim 1, wherein said supporting member consists of a central web and a pair of lateral projections thereon on which said arms of said tightening bar are pivotably mounted.

4. A tightening device as defined in claim 3, wherein said lateral projections on said supporting member are provided with bores, and pivot studs projecting from said arms of said tightening bar and engaging into said bores so as to be pivotable therein.

5. A tightening device as defined in claim 1, wherein at least a part of said arms of said tightening bar have an arcuate shape having a radius of curvature slightly larger than that of said bottom-belt roller and being spaced at small, substantially equal distances from said roller.

6. A tightening device as defined in claim 1, wherein said arms of said tightening bar are provided closely adjacent to the latter with lateral guide projections adapted to prevent said bottom belt from sliding off said tightent ing bar.

7. A tightening device as defined in claim 1, wherein said supporting member is permanently secured to said guide rail.

8. A tightening device as defined in claim 1, wherein sa d supporting member is resiliently clamped together Wll'h said guide rail.

9. A tightening device as defined in claim 8, wherein said supporting member resiliently embraces a part of said guide rail and is provided with at least one projection adapted to engage into a corresponding recess in said part.

10. tightening device as defined in claim 1, further comprising a leaf spring having one end rigidly secured to said tightening bar and the opposite end pressing against sa d supporting member for resiliently pressing said tightenmg bar Within said loop against said bottom belt so as to tighten the same.

11. A tightening device as defined in claim 1, further comprising at least one coil spring disposed above the pivot axis of said tightening means within a recess in a part projecting from said tightening bar and pressing against said supporting member for resiliently pressing said tightening bar within said loop against said bottom belt so as to tighten the same.

12. tightening device as defined in claim 4, further comprising a coil spring having a pair of coil parts spaced from each other and coaxial with said pivot studs and mounted on extensions of said studs, a central bow connecting the inner ends of said coil parts and pressing against said supporting member, and spring arms on the outer ends of said coil parts, the free end of each of said spring arms being bent at an angle and engaging into a recess in one of the arms of said tightening bar.

13. A tightening device as defined in claim 1' wherein said supporting member consists of sheet steel and said tightening means which is integral with said tightening bar consists of plastic.

14. A tightening device as defined in claim 13, wherein said tightening bar has a longitudinal recess therein, and further comprising a pin-shaped reinforcing member of a harder material secured in said recess and having a part 7 of its circumference projecting therefrom and adapted to press against the inner side of said bottom belt.

15. A tightening device as defined in claim 14, wherein the parts of said tightening bar partly encompassing said reinforcing member are provided with recesses for the insertion of a tool to permit said reinforcing member to be removed from said tightening bar.

16. A tightening device for a bottom belt of a' drawing mechanism for a spinning machine having a bottom roller and a guide rail adjacent said roller to enable said belt to run over said roller and said guide rail and to form a loop underneath said roller and guide rail, comprising tightening means for tightening the belt, said tightening means being disposed at the inner side of said belt and including arm means and engaging means adapted to engage said belt, support means on said guide rail, means for pivotably mounting said arm means on said support 8 Y means, and means associated With said arm means to facilitate assembly and disassembly of said tightening means on said supporting means.

17. A tightening device as defined in claim 16, characterized by clamping means for clamping said supporting means to said guide rail.

References Cited UNITED STATES PATENTS 3,341,901 9/1967 Kitamura 19250 FOREIGN PATENTS 915,172 1/1963 Great Britain 19250 1,064,092 4/1967 Great Britain 1925() DORSEY NEWTON, Primary Examiner 

